plm (version 1.5-12)

plm.data: Data Frame Special Format for Panel Data

Description

This function transforms a data frame in a format suitable for using with the estimation functions of plm.

Usage

plm.data(x, indexes = NULL)

Arguments

x

a data.frame,

indexes

a vector (of length one or two) indicating the (individual and time) indexes.

Value

A data.frame.

Details

indexes can be:

• a character string which is the name of the individual index variable, in this case a new variable called ``time'' containing the time index is added,
• an integer, the number of individuals in the case of balanced panel, in this case two new variables ``time'' and ``id'' containing the individual and the time indexes are added,
• a vector of two character strings which contains the names of the individual and of the time indexes.

Examples

# There are 595 individuals
data("Wages", package = "plm")
Wages <- plm.data(Wages, 595)

# Gasoline contains two variables which are individual and time indexes
# The pdata.frame is called gas
data("Gasoline", package = "plm")
Gasoline <- plm.data(Gasoline, c("country","year"))
summary(Gasoline)

# Hedonic is an unbalanced panel, townid is the individual index
data("Hedonic", package = "plm")
Hedonic <- plm.data(Hedonic, "townid")